On Wed, Jun 19, 2019 at 11:04:40AM +0200, Igor Mammedov wrote:
>On Wed, 19 Jun 2019 14:20:50 +0800
>Wei Yang <richardw.y...@linux.intel.com> wrote:
>
>> On Tue, Jun 18, 2019 at 05:59:56PM +0200, Igor Mammedov wrote:
>> >
>> >On Mon, 13 May 2019 14:19:04 +0800
>> >Wei Yang <richardw.y...@linux.intel.com> wrote:
>> >
>> >> Now MADT is highly depend in architecture and machine type and leaves
>> >> duplicated code in different architecture. The series here tries to
>> >> generalize
>> >> it.
>> >>
>> >> MADT contains one main table and several sub tables. These sub tables are
>> >> highly related to architecture. Here we introduce one method to make it
>> >> architecture agnostic.
>> >>
>> >> * each architecture define its sub-table implementation function in
>> >> madt_sub
>> >> * introduces struct madt_input to collect sub table information and
>> >> pass to
>> >> build_madt
>> >>
>> >> By doing so, each architecture could prepare its own sub-table
>> >> implementation
>> >> and madt_input. And keep build_madt architecture agnostic.
>> >
>> >I've skimmed over patches, and to me it looks mostly as code movement
>> >without apparent benefits and probably a bit more complex than what we have
>> >now
>> >(it might be ok cost if it simplifies MADT support for other boards).
>> >
>> >Before I do line by line review could you demonstrate what effect new way
>> >to build MADT would have on arm/virt and i386/virt (from NEMU). So it would
>> >be
>> >possible to estimate net benefits from new approach?
>> >(PS: it doesn't have to be patches ready for merging, just a dirty hack
>> >that would demonstrate adding MADT for new board using mad_sub[])
>> >
>>
>> Per APIC spec 5.2.12, MADT contains a *main* table and several *sub* tables
>> (Interrupt Controllere), so the idea is give a callback hook in
>> AcpiDeviceIfClass for each table, including *main* and *sub* table.
>>
>> Current AcpiDeviceIfClass has one callback pc_madt_cpu_entry for some *sub*
>> tables, after replacing the AcpiDeviceIfClass will look like this:
>>
>> typedef struct AcpiDeviceIfClass {
>> /* <private> */
>> InterfaceClass parent_class;
>>
>> /* <public> */
>> void (*ospm_status)(AcpiDeviceIf *adev, ACPIOSTInfoList ***list);
>> void (*send_event)(AcpiDeviceIf *adev, AcpiEventStatusBits ev);
>> - void (*madt_cpu)(AcpiDeviceIf *adev, int uid,
>> - const CPUArchIdList *apic_ids, GArray *entry);
>> + madt_operation madt_main;
>> + madt_operation *madt_sub;
>> } AcpiDeviceIfClass;
>>
>> By doing so, each arch could have its own implementation for MADT.
>>
>> After this refactoring, build_madt could be simplified to:
>>
>> build_madt(GArray *table_data, BIOSLinker *linker, PCMachineState *pcms,
>> struct madt_input *input)
>> {
>> ...
>>
>> if (adevc->madt_main) {
>> adevc->madt_main(table_data, madt);
>> }
>>
>> for (i = 0; ; i++) {
>> sub_id = input[i].sub_id;
>> if (sub_id == ACPI_APIC_RESERVED) {
>> break;
>> }
>> opaque = input[i].opaque;
>> adevc->madt_sub[sub_id](table_data, opaque);
>> }
>>
>> ...
>> }
>>
>> input is a list of data necessary to build *sub* table. Its details is also
>> arch dependent.
>I've got general idea reading patches in this series.
>As I've mentioned before it's hard to generalize MADT since it
>mostly contains entries unique for target/board.
>Goal here isn't generalizing at any cost, but rather find out
>if there is enough common code to justify generalization
>and if it allows us to reduce code duplication and simplify.
>
>> For following new arch, what it need to do is prepare the input array and
>> implement necessary *main*/*sub* table callbacks.
>What I'd like to see is the actual patch that does this,
>to see if it has any merit and to compare to the current
>approach.
I didn't get some idea about your approach. Would you mind sharing more light?
--
Wei Yang
Help you, Help me
